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More on Impact Factors

Giuliani, Francesco; De Petris, Michele Pio

doi: 10.1097/EDE.0b013e3181811617
Letters to the Editor

IRCCS Casa Sollievo della Sofferenza; San Giovanni Rotondo, FG, Italy

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To the Editor:

In the May 2008 issue of Epidemiology, a series of articles1 point to the limitations of the Thomson impact factor (IF), which was developed to assess journal relevance and is now unjustly being used to judge the quality of research and researchers. Other people have introduced novel (free and commercial) indicators but, nonetheless, the IF persists, as it appears so simple and has become so familiar. Recently, Los Alamos National Laboratory has launched MESUR2,3 (MEtrics from Scholarly Usage of Resources) to define and validate a range of usage-based metrics. Their method, based heavily on citation and usage data, has generated 46 metrics that provide a more-rounded view of a journal influence and prestige than the single value expressed by IF.

As the many shortcomings of IF become more apparent, the time has come for editors and scientists to consider a wider range of methods that rely on usage and social network analysis4 to judge journal and researcher relevance.

Francesco Giuliani

Michele Pio De Petris

IRCCS Casa Sollievo della Sofferenza

San Giovanni Rotondo, FG, Italy

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1. Szklo M. Impact factor: good reasons for concern. Epidemiology. 2008;19:369.
2. Bollen J, Van de Sompel H, Rodriguez MA. Towards usage-based impact metrics: first results from the MESUR Project,
3. MESUR Project. Available at:
4. Newman MEJ. Coauthorship networks and patterns of scientific collaboration, PNAS. 2004;101(suppl 1):5200–5205.
© 2008 Lippincott Williams & Wilkins, Inc.